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Added some documentation for the font module

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More to come :-)
This commit is contained in:
Simon Hausmann 2020-11-24 22:54:14 +01:00
parent 4e4d456687
commit 0f7ba74abe
1 changed files with 17 additions and 0 deletions
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17
sixtyfps_runtime/corelib/font/mod.rs
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@ -7,6 +7,9 @@
This file is also available under commercial licensing terms. This file is also available under commercial licensing terms.
Please contact info@sixtyfps.io for more information. Please contact info@sixtyfps.io for more information.
LICENSE END */ LICENSE END */
/*!
Font abstraction for the run-time library.
*/
use crate::string::SharedString; use crate::string::SharedString;
use std::cell::RefCell; use std::cell::RefCell;
use std::collections::HashMap; use std::collections::HashMap;
@ -27,6 +30,9 @@ struct FontMatch {
fonts_per_pixel_size: Vec<Rc<Font>>, fonts_per_pixel_size: Vec<Rc<Font>>,
} }
/// FontRequest collects all the developer-configurable properties for fonts, such as family, weight, etc.
/// It is submitted as a request to the platform font system (i.e. CoreText on macOS) and in exchange we
/// store a Rc<FontHandle>
#[derive(Debug, Clone, PartialEq)] #[derive(Debug, Clone, PartialEq)]
#[repr(C)] #[repr(C)]
pub struct FontRequest { pub struct FontRequest {
@ -35,10 +41,16 @@ pub struct FontRequest {
pixel_size: f32, pixel_size: f32,
} }
/// HasFont is a convenience trait for items holding font properties, such as Text or TextInput.
pub trait HasFont { pub trait HasFont {
/// Return the value of the font-family property.
fn font_family(&self) -> SharedString; fn font_family(&self) -> SharedString;
/// Return the value of the font-weight property.
fn font_weight(&self) -> i32; fn font_weight(&self) -> i32;
/// Return the value if the font-size property converted to window specific pixels, respecting
/// the window scale factor.
fn font_pixel_size(&self, window: &crate::eventloop::ComponentWindow) -> f32; fn font_pixel_size(&self, window: &crate::eventloop::ComponentWindow) -> f32;
/// Translates the values of the different font related properties into a FontRequest object.
fn font_request(&self, window: &crate::eventloop::ComponentWindow) -> FontRequest { fn font_request(&self, window: &crate::eventloop::ComponentWindow) -> FontRequest {
FontRequest { FontRequest {
family: self.font_family(), family: self.font_family(),
@ -46,6 +58,7 @@ pub trait HasFont {
pixel_size: self.font_pixel_size(window), pixel_size: self.font_pixel_size(window),
} }
} }
/// Returns a Font object that matches the requested font properties of this trait object (item).
fn font(&self, window: &crate::eventloop::ComponentWindow) -> Rc<Font> { fn font(&self, window: &crate::eventloop::ComponentWindow) -> Rc<Font> {
crate::font::FONT_CACHE.with(|fc| fc.find_font(&self.font_request(window))) crate::font::FONT_CACHE.with(|fc| fc.find_font(&self.font_request(window)))
} }
@ -63,6 +76,7 @@ impl FontCacheKey {
} }
} }
/// FontCache caches the expensive process of looking up fonts by family, weight, style, etc. (FontRequest)
#[derive(Default)] #[derive(Default)]
pub struct FontCache { pub struct FontCache {
// index by family name // index by family name
@ -70,6 +84,8 @@ pub struct FontCache {
} }
impl FontCache { impl FontCache {
/// Submits the given FontRequest to the platform's font system (i.e. CoreText) and returns the font found.
/// The result is cached, so this function should be cheap to call.
pub fn find_font(&self, request: &FontRequest) -> Rc<Font> { pub fn find_font(&self, request: &FontRequest) -> Rc<Font> {
assert_ne!(request.pixel_size, 0.0); assert_ne!(request.pixel_size, 0.0);
@ -101,5 +117,6 @@ impl FontCache {
} }
thread_local! { thread_local! {
/// The thread-local font-cache holding references to resolved font requests
pub static FONT_CACHE: FontCache = Default::default(); pub static FONT_CACHE: FontCache = Default::default();
} }